Little investigation has been made into the reproduction of pedigreed cats. A small number of studies in the literature have addressed reproductive patterns in domestic cats, covering such things as litter size and kitten mortality. Generally, these studies have used data from colonies of non-pedigreed cats kept for research purposes. Little data is available for specific pedigreed breeds of cats, and those studies available are often incomplete or out of date.

Breed-specific reproduction and kitten health data may be used to:

1. Help breeders design healthy breeding programs

2. Identify congenital diseases

3. Monitor breed health

4. Provide data to researchers to assist in studies of breed genetic diversity

Breeders of 3 pedigreed breeds (Devon Rex, Sphynx, Ragdoll) from around the world were solicited to join a study and submit data in a prospective manner. Websites were established explaining the aims of each study and mailing lists were started for study participants. Breeders enrolled their catteries in a study and were then given a cattery number to submit data confidentially. Reports could be filed online using the project website, via regular mail, or fax. Most breeders used the online report forms to submit data as this method was judged to be simple and convenient. Actual breeder participation ranged from 58 to 67% of those enrolled in each project.

Information recorded for each litter included:

1. Birth date

2. Number of live born and number of stillborn kittens

3. Congenital defects

4. Birth weights

5. Gender of kittens

Preliminary data for 3 breeds is presented. The average number of kittens per litter varied from 3.74 to 4.51 (see Table 1). Previous reports of average litter size in non-pedigreed cats ranges from 3.3 to 4.2 kittens. Reported average litter sizes for pedigreed breeds ranges from 2 to 5 kittens, although data for most breeds is scant. Pedigree cat registries may publish data on average litter size, but such data often represents only live born kittens, thus underestimating true average litter sizes.

Table 1. Litter data for 3 pedigreed breeds

Breed (# breeders)

# litters

# kittens

kittens/litter

Devon Rex (31)

201

751

3.74

Ragdoll (45)

141

636

4.51

Sphynx (18)

50

201

4.02

Table 2 records various parameters of reproduction. Average birth weight in these 3 breeds ranges from 86 to 98 grams. The average birth weight reported in the literature for cats is 100 grams. The rate of congenital defects ranged from 2.5% to 12.4% of litters. Common congenital defects included umbilical hernia, cleft palate, and flat chest kitten defect (dorsoventral flattening of the thorax). An unusual incidence of eyelid colobomas and dermal masses near the mouth has been reported in Ragdoll kittens.

Stillbirths occurred at about the same rate in all 3 breeds. Dystocia was most common in Devon Rex and uncommon in Sphynx. In Devon Rex, 25% of queens with dystocia required a c-section.

Table 2. Reproductive parameters for 3 pedigreed breeds

Breed

Average Birth Weight
(grams)

Congenital Defects
(% of litters)

Stillbirths
(% of kittens)

Dystocia
(% of litters)

Devon Rex

86

12.4

6.0

8.0

Ragdoll

98

8.5

4.9

3.5

Sphynx

97

2.5

4.5

1.0

In conclusion, this study presents preliminary data from 3 pedigreed cat reproduction and kitten health projects. It will be necessary to study each breed in order to generate relevant data and to compare data among breeds. Other studies are underway or in planning for the Burmese, Bengal, Birman, Ocicat and Norwegian Forest Cat breeds. A method for collection of prospective data specific to a breed using the Internet has been established and could be adapted to other studies.